1. Field of the Invention
The invention relates to compositions and methods for increasing the water and oil repellency of fibers in textiles, in particular in upholstery textiles, and in carpet and other floor coverings. More particularly, the invention relates to compositions containing terpolymers and fluorochemical compounds that impart strong water and oil repellency to textiles and carpet fibers, and that have good durability to shampooing or other cleaning processes.
2. Description of Related Art
Fluorinated carbon compounds have been used extensively to impart water and oil repellency to textile and carpet fibers. Part of their desirability for this use stems from their ability to provide both oil and water repellency simultaneously, unlike waxes, silicones, etc., which typically provide water repellency, but are somewhat oleophilic, and thus do not provide good oil repellency. Fluorinated or perfluorinated alkyl compounds, when applied to fibers in sufficient amount, lower the surface tension of the fiber or fabric below the surface energy of water or oils that might be spilled onto the fabric. This allows these liquids to be removed before they can penetrate into the fabric or fiber. Obviously, this is of great benefit for fibers and fabrics that are used in residential, commercial, and industrial settings, since the useful life of the fabric or fibers is substantially increased, as is their aesthetic value.
Fluorinated hydrocarbons have been predominantly made by two methods. Electrofluorination has been used by 3M Corporation and by Dainippon Ink Chemicals to directly perfluorinate a sulfonated hydrocarbon with hydrofluoric acid, ultimately producing a perfluorinated sulfonamide. This method has fallen into disfavor for environmental and health reasons. Specifically, certain of the intermediates of this process have been found to be extremely bioaccumulative.
Telomerization of tetrafluoroethylene or other fluorinated monomers, used by Asahi Glass, Atochem, Daikin, DuPont, and Clariant, has been used to produce a range of fluoroalkyl products. The telomerization process is becoming a preferred technique for producing fluorinated compounds because it does not implicate the same environmental and health concerns as the electrofluorination process.
Along with the increasing popularity of fluorochemicals produced by telomerization, there has been an increasing desire to provide telomeric fluorochemical compositions that are highly exhaustible onto nylon and other fibers of carpets and textiles. This allows these compositions to be applied in an exhaust bath, such as during dyeing, prior to sale to consumers. This, in turn, reduces or eliminates the need for purchasers and mill workers to be exposed to aerosolized fluorochemicals, and avoids the need for the surfactants typically required for foam application. It also provides for better penetration of the fiber by the fluorochemical.
One method for exhaust application of fluorochemicals onto carpet fiber has been described in U.S. Pat. No. 5,520,962, the entire contents of which are hereby incorporated by reference. In this patent, fluorochemicals are combined and applied with a particular type of stain-resist composition, which is described as xe2x80x9can anionic polymer binding compoundxe2x80x9d that is alleged to improve the performance of the fluorochemical, possibly by holding the fluorochemical to the surface of the fiber. However, even with the use of xe2x80x9canionic polymer binding compounds,xe2x80x9d the process disclosed in the xe2x80x98962 patent does not achieve the high exhaustion levels desired in the industry, and economically necessary in order to reduce waste of expensive fluorinated reagents.
In addition, there is a need for compositions that are durable, at least in the sense that the treated fibers retain a significant portion of their repellency after shampooing. In particular, shampooing using commonly available, off-the-shelf carpet or fabric shampoos, which are often highly alkaline, can cause drastic decreases in oil or water repellency, as the fluorine-containing film is washed off of the fibers or fabric along with the soil. The repellency system described in the xe2x80x98962 patent does not achieve a fluoropolymer treatment having durability levels sufficient to withstand shampooings using alkaline carpet or textile cleaning shampoos.
A composition or treatment method that meets both of these needs would decrease the amount of fluorine that is consumed during the treatment process, significantly decreasing the cost of the fabric, fiber, or process.
Finally, there is a need to provide a fluorochemical composition that has the above properties, and is also storage stable, i.e., does not undergo gelation or phase-separation over time.
This invention satisfies the needs described above by providing an exhaustion agent that can be incorporated into a stable, emulsion polymerized, repellency composition. This composition is highly exhaustible onto nylon and other fabrics, deposits a high level of fluorine onto the fibers, and is highly durable to shampooing or other cleaning treatments.
In one embodiment, the invention relates to an exhaustion agent, which is an aqueous emulsion of polymerized monomers, wherein the monomers contain:
(meth)acrylic acid (MAA);
alkyl (meth)acrylate, such as methyl (meth)acrylate (MMA); and
a substituted or unsubstituted styrene,
and wherein the average particle size of the emulsified particles is less than about 220 nm. A stable emulsion that does not undergo phase separation or gelation, and that has the requisite particle size has not been described in the patents referenced herein.
In another embodiment, the invention is a repellency enhancing composition containing a blend of a fluoropolymer, the exhaustion agent described above, and an optional hydrotrope. This composition has been found to provide theoretical or near theoretical exhaustion of fluorine onto fibers and fabrics, and the resulting oil and/or water repellency has been found to be excellent and very resistant to shampooing.
In another embodiment of the invention, the composition contains the above-described terpolymer of an MAA component, an MMA component, and a styrene component, but the terpolymer is prepared by emulsion polymerization in the presence of the fluoropolymer. While not wishing to be bound by any theory, it is believed that the terpolymer and fluoropolymer become associated, possibly by formation of an interpenetrating polymer network, and/or by other mechanisms, resulting in a high level of physical affinity of the terpolymer for the fluoropolymer, and conversely. Irrespective of mechanism, the combination of terpolymer exhaustion agent and fluoropolymer prepared in this manner are highly effective in exhausting theoretical or near theoretical levels of fluorine onto fibers or fabrics, and the resulting oil/water repellent materials have excellent durability to shampooing, as described above.
In yet another embodiment of the invention, the composition contains a polymer prepared by polymerizing the monomers of the terpolymer, in the presence of a fluoromonomer. The resulting polymer exhausts fluorine onto the fiber or fabric without any need for interaction with a separate fluoropolymer, since a single polymer provides both exhaustibility and fluorine for repellency.
The compositions of the invention provide stable fluorochemical emulsions that are highly exhaustible onto fibers and fabrics, in some cases achieving exhaustion levels of 95% to 100% of theoretical, and providing a high level of fluorine on the fiber surface, and thus providing excellent water and oil repellency. The resulting oil and water repellency provided by these compounds continues after shampooing, even with alkaline carpet or upholstery shampoos.